Justices Clarence Thomas and Samuel Alito said the ruling robbed states of their ability to decide that all killers deserve life without parole regardless of their age.

The court is using its own sense of "morality" to override that of U.S. citizens and their representatives, Thomas wrote.

While the 14-year-olds who brought the case to the high court might evoke sympathy, in fact 17-year-olds commit many heinous crimes that would justify life without parole, Alito stated.

"Even a 17-and-a-half-year-old who sets off a bomb in a crowded mall or guns down a dozen students and teachers is a 'child' and must be given a chance to persuade a judge to permit his release into society," Alito wrote, in an opinion joined by Scalia.